The present invention relates to fuel tanks for motor vehicles, in particular to Liquid Petroleum Gas (LPG) fuel tanks for motor vehicles.
For some time now the present applicant has studied and developed systems of supply via injection of LPG for engines of motor vehicles, which use a plurality of LPG injectors associated to the cylinders of the engine, which are supplied with LPG coming from a tank.
Supply systems of the type referred to above are, for example, described and illustrated in the European patent No. EP-B-0 725 205 and in the European patent No. EP-B-0 922 851 in the name of the present applicant, as well as in the corresponding patents Nos. U.S. Pat. No. 5,592,924 and U.S. Pat. No. 6,050,237. The present applicant has also filed various patent applications regarding the tank of the supply system in question and to the various electrical and hydraulic components that are associated thereto. Typically, the tank has a hollow body, within which there are housed one or more electrical components. For example, provided within the tank is a pump for supply of the LPG, designed to operate submersed in the LPG contained within the tank and actuated by an electric motor also contained within the tank. The tank is also provided with one or more level sensors that also require electrical connections.
The various pipe unions for connection of the tank with the electrical and hydraulic lines of the system for supplying LPG to the engine of the motor vehicle are provided on a closing plate that covers a mouth provided in the body of the tank. A structure of this type is, for example, described and illustrated in the European patent application No. EP 1 249 596 in the name of the present applicant. With the purpose of enabling electrical connection between the electrical components contained within the tank and the electrical lines external to the tank, the aforesaid closing plate is provided with one or more connector members that must, on the one hand, guarantee electrical connection and, on the other hand, guarantee hermetic sealing of the tank in the presence of a pressure difference between the inside of the tank and the outside, such as the one that occurs during operation with LPG supply systems of the type referred to above.
Of course, the same problem may also arise in supply systems which use different fuels, such as tanks for methane supply systems or in general any other fuel tank in which it is necessary, on the one hand, to enable electrical connection with components arranged within the tank and, on the other hand, guarantee hermetic sealing of the tank itself, in particular in the presence of a pressure jump between the inside and the outside.
FIG. 2 of the annexed drawings illustrates a connector member according to the known art, used in tanks of the type referred to above. In FIG. 2, the reference number 1 designates a portion of the wall or closing plate of the tank, which has a through opening 2, in which there is mounted a steel bushing 3 provided with a flange 4 with holes 5 (only one of which may be seen in the figure) for engagement of fixing screws to the wall 1. The bushing 3 has, on its outer surface, a circumferential groove, in which there is received a seal ring 6, which ensures tightness between the bushing 3 and the wall 1. Set within the bushing 3 is a glass disk 7, obtained by fusion directly within the bushing 3 so as to make it adhere thereto. The disk 7 is also melted directly on four conductor pins 8 (only three of which are visible in the figure), which project axially from the opposite ends of the bushing 3 and from the opposite faces of the wall 1, each conductor pin being designed to be connected at its ends respectively to a line for internal connection to the tank and to a line for external connection to the tank.
In the electrical connectors of the known type illustrated above, the glass molten directly within the steel bushing 3 and on the conductor pins 8 ensures hermetic sealing of the tank also in the presence of a pressure difference between the inside and the outside. The drawback of said known solution lies in the fact that the glass disk 7 is relatively brittle and is subject to the risk of cracking or fracturing resulting, for example, from thermal shock or possible careless manipulation of the tank or its components, particularly in the assembly and installation step. For instance, the operator responsible for installation can inadvertently deform one or more of the conductor pins 8 during their electrical connection to the respective connection terminals, with consequent mechanical stressing of the glass disk 7.
A further drawback lies in the fact that the known devices of the type referred to above are relatively complex and costly to produce.